Thread: Capi's Gyro 101
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Old 04-07-2009, 10:46 AM   #21 (permalink)
JoelKatz
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Join Date: Feb 2009
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That doesn't seem to make sense. An analog servo would then be continuously implementing new corrections, with its PID loop implemented in hardware. So there would be no advantage to digital servos at all other than frame rate. (Which would be no advantage on cyclic.)

Yes, digital servos do overshoot. The point is, they apply a reverse voltage before they overshoot (predictively). It is my understanding that an analog servo will always command the motor clockwise if it is counter-clockwise to its intended position -- thus they cannot apply reverse until they overshoot.

I think part of our disagreement may simply have to do with variation in analog servos. I'm sure manufacturers have done all kinds of tricks to improve performance.

I am 99.9% sure that the major difference between analog and digital servos, and the primary advantage of digital servos, is that if you command a small change in position on a stopped servo, an analog servo cannot command a quick motor movement, as it is responding to a small change and hence sends a small motor signal.

Obviously, on heli cyclic, if I command a slight movement, I want a slight movement *now*. It may have to overcome significant force to make that slight movement, and I expect it to do so promptly. A digital servo can apply a very brief and very extreme pulse followed by a brief and extreme reverse pulse even before it overshoots.
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